Share This

UKIRT infrared images of the four target galaxies show them in near-infrared color, where the images at different infrared wavelengths are assigned to represent red, green and blue colors. Observations with the Keck Interferometer have resolved the inner structure of the bright nucleus in all the four galaxies. The inferred ring-like structure obtained for NGC 4151 at the top-left is depicted in the top-right panel. The ring radius is 0.13 light years, corresponding to an extremely small ~0.5 milli-arcsecond angular size on the sky. The distance to each galaxy is indicated in million light-years, together with the redshift (z) of each galaxy.

Credit: M. Kishimoto, MPIfR

An international team of scientists has observed four super-massive black holes at the center of galaxies, which may provide new information on how these central black hole systems operate.

Related Articles

Their findings are published in December's first issue of the journal Astronomy and Astrophysics.

These super-massive black holes at the center of galaxies are called active galactic nuclei. For the first time, the team observed a quasar with an active galactic nucleus, as part of the group of four, which is located more than a billion light years from Earth. The scientists used the two Keck telescopes on top of Mauna Kea in Hawaii. These are the largest optical/infrared telescopes in the world.

The team also used the United Kingdom Infrared Telescope (UKIRT) to follow up the Keck observations, to obtain current near-infrared images of the target galaxies.

"Astronomers have been trying to see directly what exactly is going on in the vicinity of these accreting super-massive black holes," said co-author Robert Antonucci, a UC Santa Barbara astrophysicist.

He explained that the nuclei of many galaxies show intense radiation from X-ray to optical, infrared, and radio, where the nucleus may exhibit a strong jet -- a linear feature carrying particles and magnetic energy out from a central super-massive black hole. Scientists believe these active nuclei are powered by accreting super-massive black holes. The accreting gas and dust are especially bright in the optical and infrared regions of the electromagnetic spectrum.

Scientists can now separate the emission from the regions outside the black hole from that in the very close vicinity of the black hole. This is the location of the most interesting physical process, the actual swallowing of matter by the black hole. "While not resolving this extremely small region directly, we can now better subtract the contribution from surrounding matter when we take a spectrum of the black hole and its surroundings, isolating the spectrum from the matter actually being consumed and lost forever by the hole," said Antonucci.

To observe such a distant object sharply enough in infrared wavelengths requires the use of a telescope having a diameter of about 100 meters or more. Instead of building such a large infrared telescope, which is currently impossible, a more practical way is to combine the beams from two or more telescopes that are roughly 100 meters apart. This method, used in radio astronomy for decades, is new for the infrared part of the spectrum. This type of instrument is called a long-baseline interferometer.

The Keck telescopes are separated by 85 meters and can be used as an interferometer. Combining the light from the telescopes allows astronomers to detect an interference pattern of the two beams and infer what the black hole vicinity looks like, explained first author Makoto Kishimoto, of the Max Planck Institute for Radio Astronomy in Bonn, Germany.

Kishimoto and Antonucci have a longstanding research collaboration, which began with Kishimoto's post-doctoral fellowship with Antonucci in the UCSB Department of Physics a decade ago. Antonucci points out that most of the credit for this current work goes to Kishimoto.

In 2003, astronomer Mark Swain at the Jet Propulsion Laboratory and his collaborators used the Keck Interferometer to observe the material accreting around one super-massive black hole, called NGC 4151. This is one of the brightest black holes in the optical and infrared wavelengths. The observations provided astronomers with the first direct clue about the inner region of a super-massive black hole system, said Antonucci.

"The results looked puzzling in 2003," said Kishimoto. "But with the new data and with more external information, we are quite sure of what we are seeing." According to the team's results, the Keck Interferometer has just begun to resolve the outer region of an active galactic nucleus's accreting gas, where co-existing dust grains are hot enough to evaporate, transitioning directly from a solid to a gas.

The W. M. Keck Observatory is a scientific partnership of the California Institute of Technology, the University of California, and NASA.

University of California - Santa Barbara. (2009, December 11). Super-massive black holes observed at the center of galaxies. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/2009/12/091210173609.htm

More From ScienceDaily

More Space & Time News

Featured Research

Mar. 31, 2015  Astronomers have conducted observations of the massive-star forming region IRAS 16547-4247. The observation results shows the presence of multiple, or at least two, gas outflows from a protostar, ... full story

Mar. 30, 2015  Observations made with two space observatories, Herschel and Planck, reveal glimpses into how today's galaxies came to be. Using one-of-a-kind instrumentation, astronomers were able to study large ... full story

Mar. 30, 2015  Stars form when gravity pulls together material within giant clouds of gas and dust. But gravity isn't the only force at work. Both turbulence and magnetic fields battle gravity, either by stirring ... full story

Mar. 30, 2015  Scientists have long puzzled over the planet Mercury's excessively dark surface. New research suggests that carbon from passing comets could be the planet's mystery darkening ... full story

Mar. 30, 2015  Luke Skywalker's home in "Star Wars" is the desert planet Tatooine, with twin sunsets because it orbits two stars. So far, only uninhabitable gas-giant planets have been identified circling such ... full story

Mar. 26, 2015  Astronomers have studied how dark matter in clusters of galaxies behaves when the clusters collide. The results show that dark matter interacts with itself even less than previously thought, and ... full story

Mar. 26, 2015  The best observations so far of the dusty gas cloud G2 confirm that it made its closest approach to the supermassive black hole at the centre of the Milky Way in May 2014 and has survived the ... full story

Mar. 25, 2015  Researchers have completed a new analysis of an ancient Martian lake system in Jezero Crater, near the planet's equator. The study finds that the onslaught of water that filled the crater was one of ... full story

Mar. 25, 2015  The precise measurement of Saturn's rotation has presented a great challenge to scientists, as different parts of this sweltering ball of hydrogen and helium rotate at different speeds whereas its ... full story

Related Stories

Feb. 18, 2015  Every massive galaxy has a black hole at its center, and the heftier the galaxy, the bigger its black hole. But why are the two related? After all, the black hole is millions of times smaller and ... full story

Oct. 17, 2013  Massive black holes of more than one million solar masses exist at the center of most galaxies. Some of the massive black holes are observed as active galactic nuclei (AGN) which attract ... full story

Jan. 30, 2013  Astronomers report the exciting discovery of a new way to measure the mass of supermassive black holes in galaxies. By measuring the speed with which carbon monoxide molecules orbit around such ... full story

Nov. 28, 2012  Astronomers have discovered a black hole that could shake the foundations of current models of galaxy evolution. At 17 billion times the mass of the Sun, its mass is much greater than current models ... full story

Jan. 9, 2011  The discovery of a relatively nearby dwarf galaxy with a supermassive black hole shows astronomers what young galaxies in the very early Universe probably were like. It also greatly strengthens the ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.